In the context of Horndeski gravity explored in this paper, a tight bound on \(\delta c_{\rm GW}\)  from LISA would therefore firmly reduce the set of surviving scalar-tensor dark energy theories to [1]}, [2]}, [3]}, [4]} (also see [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [14]}, [16]} for closely related prior work)
\( {\cal L} = G_2(\phi , X) + G_3(\phi ,X)\Box \phi + G_4(\phi )R,\) 
